Abstract

We present a completely numerical method of calculating one-loop amplitudes. Our approach is built upon two different existing methods: the contour-deformation and the extrapolation method.
Taking the best features of each of them, we devised an intuitive, stable and robust procedure which circumvents the problem of large cancellations and related numerical instabilities, by calculating the complete amplitude at once. After extensively testing our method on various one-loop processes, we report results on the 2γ → (N − 2)γ benchmark process.